P-041 - Hybridization and polyploidization are associated with expanded effector-triggered immunity profiles in oilseed crops

Effector-triggered immunity (ETI) occurs when plant nucleotide-binding leucine-rich repeat receptors (NLRs) recognize pathogen effectors, eliciting a strong defense. ETI is common in interactions between the bacterial pathogen Pseudomonas syringae and Arabidopsis thaliana. However, whether this translates to related crop species is unknown. Here, we present a systematic screen of the ETI landscapes in brassicaceous oilseeds Brassica napus (canola) and Camelina sativa (false flax) using 529 P. syringae effectors. We identified ETI-eliciting alleles from 29 and 36 effector families in B. napus and C. sativa, respectively. We mapped ETI-elicitor homologs onto a P. syringae phylogeny, revealing that 79% and 88% of strains carry three or more B. napus and C. sativa ETI-elicitors, indicating significant ETI load against P. syringae in oilseeds. Oilseed ETI landscapes are expanded relative to A. thaliana, and the number of ETI responses is correlated with the species’ NLR repertoire size, which is proportional to ploidy. Interestingly, while the A. thaliana ETI profile is smaller than the two oilseed crops, A. thaliana ETI responses are generally stronger. Further, the A. thaliana ZAR1 NLR has a much broader effector recognition spectrum than ZAR1 in B. napus or C. sativa. This study is the first comparative analysis of ETI potential against an important plant pathogen using model and crop lineages, highlighting both ETI conservation and the divergence of recognition mechanisms.